1. Field of the Invention
The present invention relates to a head lamp for a vehicle, and more particularly, to a head lamp for a vehicle having a discharge bulb. Although the present invention is suitable for a wide scope of applications, it is particularly suitable for preventing a user from replacing a discharge bulb while battery power is supplied to a starting circuit.
2. Description of the Related Art
Recently, a discharge bulb has been increasingly employed as a light source of a head lamp for a vehicle because of its high luminance irradiation capability. In order to light up the discharge bulb, a high voltage has to be applied to the discharge bulb. A power supply voltage may be as high as 20 kV in supplying the voltage to the discharge bulb through a high voltage cord. A starting circuit is provided between the discharge bulb and a battery power supply for the head lamp having the discharge bulb.
Generally, an opening portion for replacing a discharge bulb is formed in a lamp body which accommodates the discharge bulb such that the bulb is taken out from or inserted into the lamp body through the opening portion for the bulb replacement. Except when the bulb is replaced, the opening portion is covered with a back cover for preventing dust or the like from entering into the lamp body.
In the head lamp for a vehicle having the discharge bulb as described above, a user inserts his/her fingers into the lamp body through the opening portion for replacing the bulb. In this occasion, the user's fingers may touch a high voltage cord, and a socket for connecting the discharge bulb. Assuming that power is continuously supplied to the discharge bulb during the bulb replacement, the user would be in danger of being exposed to the high voltage in the case where the high voltage cord is broken or the user touches a terminal portion of the socket with his/her the fingers. Therefore, there is a need for a safe device to prevent the user from replacing the bulb while the battery power is supplied to the starting circuit.